I hate to Denny this up for you but we're talking about an NRA add that's purposed to increase membership. My beef with it all along is that it's aimed at the right. We're not going to win with echo-chambers. They have theirs too. I think our best weapon is cognitive dissonance. Blow their minds with truth. Instead the NRA chooses to recruit from the same usual tribe.
Clearly it's not an "echo chamber" (I hate that phrase), with this topic in evidence. While those who object to the add may not self-identify as "the right," those who oppose the individual RKBA absolutely would lump anyone who supports IRKBA as "the right" or worse (in their minds).
Given the level of noise in our society, I don't think you can reason with people and blow their minds with the truth unless and until you actually get their attention. Dana Loesch's ad is getting attention. Perhaps a better approach would have been to incorporate additional, less aggressive messaging in the same piece. Get the attention, then apply the reason and logic and blow minds with the truth.
You can't blow a single mind with the truth if it's not paying any attention to you. Ask any school teacher.